This invention relates to a control device for a plurality of rotating electrical machines.
Tokkai-Hei-11-275826 published by the Japanese Patent Office in 1999 discloses a control device for a plurality of rotating electrical machines which are independently controlled by a single inverter of the control device. This control device supplies all the rotating electrical machines with a composite current obtained by combining alternating currents for the rotating electrical machines which flow in accordance with the rotational phases of respective rotors.
However the prior-art control device still requires improvements to the efficiency of the rotating electrical machine and the efficiency of the inverter in order to prevent the generation of heat.
It is therefore an object of this invention to improve the efficiency of a system which includes a plurality of rotating electrical machines and a control device having a single inverter for supplying a composite current for the plurality of rotating electrical machines.
In order to achieve above object, this invention provides a control device for a rotating electrical machine system having a plurality of rotating electrical machines, the rotation of each rotating electrical machine being controlled by a current flowing in response to the rotational phase of a rotor thereof, the control device comprising a single current control circuit which is connected to the plurality of rotating electrical machines and produces a composite current comprising the current for each rotating electrical machine; and a controller.
The controller functions to set an operating point of at least one rotating electrical machine; set an operating point of the other rotating electrical machine in response to the set operating point so that either the efficiency of the current control circuit or the overall efficiency with respect to all of the rotating electrical machines and the current control circuit is maximized; set the current for each rotating electrical machine based on the set operating points of all the rotating electrical machines; and control the current control circuit so that the current control circuit produces the composite current for all rotating electrical machines.
The details as well as other features and advantages of this invention are set forth in the remainder of the specification and are shown in the accompanying drawings.